shady groundcover under ash tree
I have a fairly large area surrounding an ash tree that isn't reached by the sprinkler system and is now used as a digging area by a Golden retriever, 11-mo.-old puppy, and it's also used as a way to bring dirt into the house. So I'm thinking if it were planted, she wouldn't dig there. I don't want anything that has deep roots that would hurt the ash tree. I'm thinking that until the area is filled in by groundcovers, I could put lots of bark chips there. There is a garden area to the south of this area, and my yard faces north and also has a western exposure, but it's surrounded on both the north and west by a 6' fence.
I've been told to put a sandbox on part of the area and let my dog dig in that, but I don't know if she'd think that was a good substitute for dirt. I could fix a digging area for her in the dirt, but that would still mean we'd have to have a foot wash before she could come back in to the house, at least if it was a little muddy.